Device for applying a selected moisture content to a web made of a fibrous material

ABSTRACT

A dampening device applies a selected moisture content to a fibrous web such as a paper or textile web by spraying liquid in nebulized form upon the web. Solid, liquid or gaseous additives may be included in the stream of nebulized liquid at selected proportions. The liquid and the additives, if any, are nebulized by feeding flows of liquid plus additives, if used, and air to spray nozzles which nebulize the liquid by the action of the air flows and direct cones of nebulized liquid upon the web in uniform distribution and at a minimum impact pressure thereby effectively avoiding spotting, discoloration and excessive moistening of the web material.

Unite States Patent 91 Pleines [54] DEVICE FOR APPLYING A SELECTEDMOISTURE CONTENT TO A WEB MADE OF A FIBROUS MATERIAL [76] Inventor:Hanns Dieter Pleines, Benzstrasse 47-49, Sprendlingen-Hessen, Germany 22Filed: Sept. 24, 1970 21 Appl.No.:75,143

[52] US. Cl. ..239/341, 239/416, 162/310 [51] Int. Cl. ..B05b'7/32 [58]Field of Search ..162/265, 310;

Biber et a1. ..239/424 X 2,606,069 8/1952 Hutchins et al. 239/305 X2,361,144 10/1944 Leopsinger.. ...239/424 X 2,516,401 7/1950 Marcuse..239/424 X 2,951,007 8/1960 Lippke ..162/310 X 3,304,011 2/1967 Paasche..239/305 [451 May 29,1973

Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. LoveAttorney-Plane, Baxley & Spiecens [5 7] ABSTRACT A dampening deviceapplies a selected moisture content to a fibrous web such as a paper ortextile web by spraying liquid in nebulized form upon the web. Solid,liquid or gaseous additives may be included in the stream of nebulizedliquid at selected proportions. The liquid and the additives, if any,are nebulized by feeding flows of liquid plus additives, if used, andair to spray nozzles which nebulize the liquid by the action of the airflows and direct cones of nebulized liquid upon the web in uniformdistribution and at a minimum impact pressure thereby effectivelyavoiding spotting, discoloration and excessive moistening of the webmaterial.

6 Claims, 6 Drawing Figures Patented May 29, 1973 3,735,929

2 Sheets-Sheet l o o 0%) Q INVENTOR. 2 HAN/VS D/ETER PLE/NES PatentedMay 29, 1973 2 Sheets-Sheet 3 FIG. 3

w s N .5 k RN a ma (WM NL EP M V we maw E M 0 i s N W MMH H l DEVICE FORAPPLYING A SELECTED MOISTURE CONTENT TO A WEB MADE OF A FIBROUS MATERIALThe invention relates to a dampening device for applying nebulized oratomized liquid upon a web made of fibrous material such as paper,cardboard, textiles, etc., and more particularly, to a dampening deviceof this kind for applying a selected moisture content to a web conveyedalong a path intersecting sprays of nebulized liquid. The term web asused herein is intended to encompass a continuous web and also a webformed by successive sheets.

BACKGROUND There are known dampening devices of the general kind abovereferred to which comprise two or more spray nozzles which are disposedin a row transverse of the conveying direction of the web to bemoistened. The purpose of devices of this kind is to control themoisture content of the web, such as a paper web, so that the tendencyof such webs to become more or less wavy, especially along the edges, iscounteracted or at least reduced. Moreover, moistening of the paper alsoserves to smooth the surface of the material by pressing loose andpossibly protruding fibers into slight depressions normally present inthe surface so that such fibers become embedded in such impressions andthus fill the same. In other words, it is desired that all the fibers ofwhich the material is composed are within the surface plane of thematerial.

Moistening of fibrous webs is also an important part of the processsteps used for calendering or glazing the surface. While moistening canbe eflected by using pure water as spray medium, it is often advisableto add special fillers and other substances to the water as itis wellknown in the art. Such additives produce on a fibrous web such as apaper web the glaze or gloss which is desired and often required inpractice on paper, cardboard, packaging material, etc.

As it is well known, application of the moisture must be effected verycarefully and in nebulized or atomized form, as otherwise finished paperor other fibrous material will show surface spotting ordulling.Excessive moistening also results in sponginess of the material and thusin correspondingly reduced strength. Moreover, application of moisturewithout sufficient nebulization or atomization of the spray medium maycause spattered surfaces and formation of stripes. As it is evident, allsuch surface defects reduce the market value of the finished product andmay even result in waste of the producedpaper.

It has been proposed to use very large calenders to prevent the aforedescribed faulty application of moisture. However, the use of largecalender units requires correspondingly large space and also accessoriesto an extent which is often not commercially acceptable. Wear and tearis increased: service and repair costs are also increased and thetemporary stopping'of a large unit causes a correspondingly large lossof production.

There are also known dampening devices which direct a forceful stream ofliquid spray medium upon the web to be moistened. The resulting forcefulimpact of the liquid, often in the form of rather large drops, upon theweb tends to cause the afore indicated surface detects and, hence is notsatisfactory in practice.

THE INVENTION It is a broad object of the invention to provide a noveland improved dampening device of the general kind above referred to bymeans of which the desired moisture content can be sprayed upon afibrous web such as a paper, cardboard or textile web in finelynebulized or atomized form and at a minimum impact pressure, therebyavoiding the afore pointed out disadvantages of conventional deviceswhich direct the liquid spray medium upon the web at considerable force.

Another important object of the invention is to provide a novel andimproved dampening device of the general kind above referred to whichpermits inclusion of additives such as chemical additives in gaseous orliquid form at selected proportions in water sprayed upon the web innebulized or atomized form.

Still another important object of the invention is to provide a noveland improved dampening device of the general kind above referred towhich includes a plurality of spray nozzles arranged in a row transverseof the path of travel of the web to be moistened and individuallycontrollable, thereby assuring that the entire width of the web iscontinuously and uniformly moistened to the selected extent.

SUMMARY OF THE INVENTION The afore pointed out objects, features andadvantages, and other objects, features and advantages which will bepointed out hereinafter, are obtained by providing a dampening devicewhich comprises one or more spray nozzles each including a first ductfor a spray medium in liquid form and a second duct for a spray mediumin gaseous form. Each of the ducts terminates at one end in a nozzleopening, the nozzle opening of the second duct encompassing the nozzleopening of the first duct so that liquid emanating from the nozzleopening for the liquid is mixed with the air flow emanating from thesecond nozzle opening thereby forming a solid spray cone of finelynebulized liquid.

Liquid and pressurized air are supplied to the ducts for each nozzlethrough conduits connected to suitable sources of supply. Chambersincluded in the conduits connected to the spray nozzles for supplyingliquid thereto serve to provide a supply of liquid in substantiallypressure-free condition so that the moisture forming the streams ofnebulized liquid reach the web at a minimum pressure.

A plurality of spray nozzles is preferably arranged in a row transverseof the path of travel of the web to be moistened, and a control panel isprovided by means of which the streams of nebulized liquid emanatingfrom the nozzles can be individually regulated. The control panelfurther includes means for supplying suitable and conventionally usedadditives to the streams of nebulized liquid at selected and adjustableproportions.

DETAILED DESCRIPTION OF THE INVENTION In the accompanying drawing, apreferred embodiment of the invention is shown by way of illustrationand not by way of limitation.

In the drawings:

FIG. 1 is a lengthwise view, partly in section, of a spray nozzle asincluded in the dampening device according to the invention;

FIG. 2 is an elevational diagrammatic view of the dampening device:

FIG. 3 is a sectional elevational view of a control panel for supplyingadditives at selected proportions;

FIG. 4 is an enlarged view, partly in section, of an assembly forsupplying liquid to the spray nozzles;

FIG. 5 is a diagrammatic view of an assembly for supplying air to thespray nozzles; and

FIG. 6 is a sectional fragmentary view of a nozzle.

Referring now to the figures more in detail, it should first be pointedout that while only one spray nozzle and the conduits connected theretoare shown in detail, the device generally includes several such spraynozzles disposed in a row across the path of travel of a paper web to bemoistened and each connected to the necessary conduits, the flow ofspray media to the nozzles being individually controllable, as will bemore fully described hereinafter.

The dampening device as exemplified serves to apply the desired moisturecontent, with or without the use of additives, to a web such as a paperweb 38 continuously withdrawn from a supply drum 39 at a required andsubstantially constant speed. The web is guided past spray nozzles 8 ofthe device, as it is clearly shown in FIG. 2. The transport and theguidance of the web do not constitute part of the invention, and arehence not shown in detail.

Turning now to the dampening device itself, the device comprises afilter l to which liquid, usually water, is supplied through a pipe 2which should be visualized as being connected to a suitable source ofwater. Filter 1, which is presumed to be conventional, is connected by apipe 3 including a manometer 4 and a flow meter 5 to a control panel 6,which will be more fully described hereinafter. The panel, in turn, isconnected by pipes 7 to spray nozzles 8 for supplying liquid thereto. Aspreviously stated, and as also shown in FIG. 4, several such pipes 7,which may be made of rubber or plastic, extend from the control panel,one for each nozzle in the row.

The dampening device further comprises an air compressor 9, which isconnected by a pipe 10 to a collector 32, which may and generally doesinclude an air filter.

A tubular bracket 35 is secured to the frame structure 50 of the device.The bracket supports control panel 6 and an arm 35a which in turn,mounts a connector 16 for each of the spray nozzles.

The collector 32 is connected to a pipe 17 which, in turn, is connectedto an air chamber 27c in control section 12 as is clearly shown in FIG.2. The chamber is connected via pipes 27b and a manometer 27d to spraynozzles 8. The flow of pressurized air and gaseous additives, if any,through pipes 17 is controlled by means of control buttons 13, 14 and 15and valves 60 associated therewith.

Water and liquid additives are supplied to spray nozzles 8 via pipe 3, achamber 62 and pipes 7. The flow of water and liquid additives iscontrolled by means of buttons 18, 19 and 20 on control panel 6. Thesebuttons and associated valves 61 individually controllable by thebuttons for each nozzle selectively direct the flow of the water intogauges 21, 22 and 23 of the kind permitting visual observation of thelevel of liquid therein. While the air supplied to the spray nozzles isunder pressure the spray water and liquid additives are practicallywithout pressure. Accordingly, distribution of liquid as sucked off bythe pressurized air in pipe 17 and directed by the spray nozzles 8 uponpaper web 38 is at minimum pressure, as desired.

The respective end of each expansion sleeve is threaded into a threadedbore 29 of the respective connector 16. Each nozzle 8 comprises an innermember 30 which defines a duct 30a. One end of this duct is connected byan extension 31 and a threaded sleeve 41 to the respective liquidcarrying pipe 7 while the other end terminates in nozzle opening 30b. Anouter member 24 encompasses inner member 30 and defines in conjunctiontherewith a nozzle opening 24a for pressurized air and gaseousadditives, if any. Nozzle opening 24a which has a circular cross sectioncoaxial with nozzle opening 30b for liquid, encompasses nozzle opening30b and is connected with a space 36 within an expansion sleeve 27a viaone or more tangentially directed grooves 51 in the inner wall of outerspray nozzle member 24 as it is best seen in FIG. 6. As a result, arotational movement is imparted to the gaseous media as the same emanatefrom nozzle opening 24a.

As stated before, each spray nozzle 8 is mounted on a connector 16 bymeans of the expansion sleeve 27a which, in turn, is secured to athreaded extension 25 of outer member 24 of the respective spray nozzleby a threaded sleeve or cap 28.

Air pipe 17 and pipes 27b for additives as supplied from control section12 connect to a tubular carrier 26 supported by arm 35a. Pipes 27b,which may be hoses made of rubber or a pliable plastic, are disposedwithin carrier tube 26 as it is clearly shown in F IG. 3. Tube 26 isconnected to expansion space 36 through a narrow bore 33. The volume ofthe expansion space can be reduced or enlarged by screwing cap 28 moreor less upon threaded extension 25 of outer member 24 of spray nozzle 8as it is best shown in FIG. 6. A spring 40 disposed between cap 28 andsleeve 27a biases a shoulder 27e against a flange 28a of the cap so thatthe expansion space has the desired volume.

The device of the invention can also be operated without providingcontrol section 12 in which case the air operated components therein andpipes 27b may be omitted. The air pipe 17 is then arranged as it isshown in FIGS. 2 and 3 in dotted lines, that is, it is directlyconnected to connector 16. A simplified arrangement of this kind issufficient for many purposes.

As it is now apparent, the spray nozzles are supplied with liquid spraymedium and also with pressurized air with or without the admixture ofadditives. The location of the nozzle openings 24a and 30b relative toeach other can be adjusted by axially displacing the outer nozzle member24 relative to the inner member 30. A screw connection 52 is providedfor the purpose.

The connectors 16 are preferably disposed in a row mounted for instance,on tube 35. The spray nozzles should be spaced so that the spray cones37 emanating from the nozzle openings fully cover the area of web 38 butwithout marginal overlap as such overlap would cause the formation oflarger drops.

The device of the invention permits application of moisture upon the webwithout or at least practically without pressure upon the surface of web38. The operation of the device is so simple that semi-skilled labor canbe employed instead of highly trained correspondingly expensivespecialists. The nebulization at a very low pressure of the sprayedwater and the additives, if any, used for dampening the web produces, ineffect a continuous film of water which prevents the formation ofstripes and dry area portions on the web. Moreover, the use of minute oreven micro-sized water particles facilitates the penetration of themoisture into the web. It is well known in the art that spraying ofcomparatively large drops of water upon the web unavoidably results in ahigh percentage of wastage. Formation of comparatively large dropsoccurs when the spray cones are not oriented exactly in side by siderelationship but overlap at the margins. Such overlap causes thedroplets of adjacent cones to combine thereby becoming accordinglylarger.

The carrier tube 26 and thus the pipes 17 and 27b therein and/or bracket35 can be pivotally mounted so that the spray cones 37 can beconveniently adjusted for the operationally correct angle relative tothe plane of web 38.

Summing up, the water supply in gauges 21, 22 and 23 is practicallywithout pressure. It is sucked out of the gauges by the rotation of theair flow as caused by grooves 51 when the air flow is forced throughnozzle opening 240. The sucked-on water is nebulized as it emanates fromnozzle opening 30b. Due to the low air pressure in the spray nozzle thenow nebulized moisture drops upon the web substantially only by gravityrather than by pressure, that is, the moisture floats upon the web.Moreover, the spray cones contain substantially the same percentage ofmoisture throughout their cross section while with dampening devices asnow known the 'spray cone is a hollow cone. As is evident, the use of acone containing substantially the same moisture content at its entirecross section produces the desired moistening of the web withoutformation of stripes or dry area portions thereon.

While the invention has been described in detail with respect to acertain now preferred example and embodiment of the invention, it willbe understood by those skilled in the art, after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention, and it isintended, therefore, to cover all such changes and modifications in theappended claims.

What is claimedis:

l. A dampening device for applying a selected moisture content to a webmade of a fibrous material, said dampening device comprising incombination:

at least one spray nozzle including a first duct for a spray medium inliquid form and a second duct for a spray medium in gaseous form, eachof said ducts terminating at one end in a nozzle opening, thenozzle'opening of the second duct encompassing the nozzle opening of thefirst duct, said spray nozzle having an inner member defining saidsecond duct and encompassing said inner member, said members beingaxially displaceable with reference to each other therebycorrespondingly varying the stream of nebulized spray media as emanatingfrom said nozzle openings;

first conduit means for connecting a supply of liquid spray medium tothe other end of the first duct; second conduit means for feeding a flowof gaseous spray medium to the other end of the second duct; storagemeans included in the first conduit means for collecting therein asupply of the liquid spray medium substantially free of pressure;control means included in said conduit means for controlling the supplyof liquid in said storage means; and

an air expansion chamber included in the second conduit means forreducing in said chamber the pressure of gaseous spray medium passingthrough said second conduit to a pressure slightly above atmosphericpressure;

whereby the air flow emanating from the nozzle opening of the secondduct sucks out liquid contained in said storage means and sprays thesuckedout liquid in nebulized form upon the web to be moistened.

2. The device according to claim 1 wherein said storage means comprisegauges providing for visible observation of liquid therein.

3. The device according to claim 1 wherein the second duct has a crosssection encompassing the first duct and includes adjacent to its nozzleopening a portion tapered toward the juxtaposed portion of the firstduct.

4. The device according to claim 3 wherein facing inner walls of saidmembers include guide means imparting a rotary motion to the air flowemanating from the nozzle opening of the second duct.

5. The device according to claim 4 wherein said tapered duct portion hasin a boundary wall an elongate groove slanted relative to the lengthwiseaxis of said tapered portion thereby imparting said rotary motion to theair flow emanating from the nozzle opening of the second duct.

6. The device according to claim 1 wherein adjustment means are providedfor varying the volume of said expansion chamber, said adjustment meansincluding members for selectively changing the distance between twoboundary walls of said chamber.

manna:

1. A dampening device for applying a selected moisture content to a webmade of a fibrous material, said dampening device comprising incombination: at least one spray nozzle including a first duct for aspray medium in liquid form and a second duct for a spray medium ingaseous form, each of said ducts terminating at one end in a nozzleopening, the nozzle opening of the second duct encompassing the nozzleopening of the first duct, said spray nozzle having an inner memberdefining said second duct and encompassing said inner member, saidmembers being axially displaceable with reference to each other therebycorrespondingly varying the stream of nebulized spray media as emanatingfrom said nozzle openings; first conduit means for connecting a supplyof liquid spray medium to the other end of the first duct; secondconduit means for feeding a flow of gaseous spray medium to the otherend of the second duct; storage means included in the first conduitmeans for collecting therein a supply of the liquid spray mediumsubstantially free of pressure; control means included in said conduitmeans for controlling the supply of liquid in said storage means; and anair expansion chamber included in the second conduit means for reducingin said chamber the pressure of gaseous spray medium passing throughsaid second conduit to a pressure slightly above atmospheric pressure;whereby the air flow emanating from the nozzle opening of the secondduct sucks out liquid contained in said storage means and sprays thesucked-out liquid in nebulized form upon the web to be moistened.
 2. Thedevice according to claim 1 wherein said storage means comprise gaugesproviding for visible observation of liquid therein.
 3. The deviceaccording to claim 1 wherein the second duct has a cross sectionencompassing the first duct and includes adjacent to its nozzle openinga portion tapered toward the juxtaposed portion of the first duct. 4.The device according to claim 3 wherein facing inner walls of saidmembers include guide means imparting a rotary motion to the air flowemanating from the nozzle opening of the second duct.
 5. The deviceaccording to claim 4 wherein said tapered duct portion has in a boundarywall an elongate groove slanted relative to the lengthwise axis of saidtapered portion thereby imparting said rotary motion to the air flowemanating from the nozzle opening of the second duct.
 6. The deviceaccording to claim 1 wherein adjustment means are provided for varyingthe volume of said expansion chamber, said adjustment means includingmembers for selectively changing the distance between two boundary wallsof said chamber.